A lithium-ion secondary battery has a characteristic that it has a higher energy density than other secondary batteries and is operable at a high voltage. Therefore, it is used for information devices such as cellular phones, as being a secondary battery which can be easily reduced in size and weight; and nowadays there are increasing demands for the lithium-ion secondary battery to be used as a power source for large-scale apparatuses such as electric vehicles and hybrid vehicles.
The lithium-ion secondary battery comprises a cathode layer and an anode layer (a pair of electrode layers), and an electrolyte disposed between these. The electrolyte is constituted for example by a non-aqueous liquid or a solid. When the liquid is employed as the electrolyte (hereinafter the liquid being referred to as an “electrolytic solution”), it easily permeates into the cathode layer and the anode layer. Therefore, it is possible to easily form an interface between the electrolyte and an active material contained in the cathode layer and the anode layer, and to easily improve the performance of the battery. However, since widely-used electrolytic solutions are flammable, it is necessary to mount a system to ensure safety. By contrast, electrolytes in solid form (hereinafter referred to as “solid electrolytes”) are nonflammable, thus enabling simplification of the above system. As such, a lithium-ion secondary battery provided with a layer containing the nonflammable solid electrolyte (hereinafter the battery being referred to as a “solid battery”) has been proposed.
As a technique related to such a solid battery, Patent Document 1 for example discloses a batter comprising: a positive electrode containing a source of mobile alkali metal ions on charge; an alkali metal negative electrode; and a polymer electrolyte. In addition, Patent Document 2 discloses a solid electrolyte secondary battery comprising: a battery cell having a cathode containing a cathode active material capable of absorbing and releasing lithium, an anode containing an alloy-type anode active material, and a solid electrolyte containing a polymer or a separator containing the solid electrolyte; and a control means to control the battery cell at the time of discharge to have a temperature equal to or greater than a temperature that enables the polymer to be deformed.